AHU - air handlers or air handling units were designed for air regulation and circulation in HVAC systems.Its main function is to provide air exchange and treatment (pressing, filtering, heating, cooling, humidifying, air drying) distributed by the ventilation system of the building or its parts. In the air handling unit the following essential components are: filters, heating and/or cooling elements, humidifier, mixing chamber, blower/fan, balancing, heat recovery device, controls, vibration isolators. There are small air handling units known as terminal units and then we have large air handlers. If there is more complex air treatment in the unit (eg drying or humidification), then we can talk about the air conditioning unit. The definition of the air handling unit is not specified and both terms are sometimes used interchangeably. Ventilation units can be used in both single family or small service buildings as well as large office, retail or manufacturing facilities. Within an hour they can exchange air with volume from tens of m3 to tens of thousands of m3. Depending on the application and technical parameters, they can have very different construction, often very complex.Air handling units - a way for good air quality In office buildings or utility buildings, mechanical ventilation is practically standard, and even in residential buildings, small ventilation units with heat recovery start to host.The air handling and ventilation and air handling units are the main equipment for the distribution and pre-treatment of fresh air. Fans that are also the main source of operating costs of the whole system are the element that performs this function. Modern units must therefore be equipped with fans with the most energy-efficient motors and their operation should be regulated to the widest extent possible. An example is the use of an open-ventilated fan with the ability to measure the airflow at four points, so that the operation of the device is controlled on a regular basis, reducing the electricity consumption.The air handling unit performs several processes, which requires proper equipment. In modern units, efforts are being made to minimize the impact of these devices, so that they are not another source of energy. That's why an important function is automation that spins sensor and actuator systems into a single, well-functioning ventilation system. New drivers have the option to select several communication protocols that use the system to perform current air preparation tasks for specific parameters, but also provide the user with valuable information, allowing him or her to keep up to date with the system. The built-in Web server allows for control and monitoring of the control panel via a web page, giving the user a more complete and convenient insight into the information than the driver screen. The new units can also be plugged into the BMS, which, especially for large objects, makes it easy to control the ventilation, also remotely via GSM messages.New ventilation units are becoming more efficient and energy-efficient, so they can work in high-demand buildings. Leading manufacturers in the United States are Carrier Corporation, Trane, Emerson Network Power, Rheem, Lennox International, Daikin Industries, Trox.